Grain weight, density, and moisture measurements are of importance to farmers and grain harvesters in all regions around the world. These measurements enable determinations to be made and conclusions to be drawn with respect to farming practices and all aspects that affect crop yield. To properly understand and analyze variable that affect grain crop production, it is important to acquire grain weight, density, and moisture measurements which can be mapped to precise locations in the field. Preferably, such precision mapping will plot grain characteristics for a given plot of harvested grain.
Over the years, many efforts have been made to weigh and measure characteristics of crop yields. For example, crop yields have been monitored by harvesting a relatively large area, and then measuring the volume or mass of grain harvested from the area. Such methods are inadequate, however, because they are labor intensive, they lack proper spatial resolution, and the do not provide sufficient data accuracy for assessment of on-farm research results or site-specific agronomic practices.
Other methods of monitoring crop yield have been recently attempted. Measurements related to grain flow in the clean grain system of the combine have been suggested. One system monitors the power required to turn the clean grain auger at the bottom of the combine. Another monitors the pressure of grain coming over the top of the clean grain elevator by placing metal "fingers" on load cells in the grain stream. Yet another system tries to monitor the level of grain in the grain bin. In each of these methods, grain flow is monitored to produce yield information. The basic problem with respect to each of these systems, however, is that they all involve calibrated methods that have limited accuracy. The indicated grain flow varies depending upon the moisture, density, and possibly temperature of the grain. Furthermore, output of the particular sensor may not be linear with grain flow, which could cause further errors.
Some traditional grain harvesters have measured characteristics of grain by feeding a small container and taking measurements of the grain while in the small container. One example is U.S. Pat. No. 5,173,079. This patent discloses a grain measuring and weighing system wherein a suspended bucket is filled so that grain inside the suspended bucket can be measured and weighed. In an alternative embodiment, this patent discloses the concept of weighing the actual grain storage bin to determine the grain characteristics. Such a system is incapable, however, of obtaining adequate and sufficient statistical information on the grain harvest to enable accurate plotting of grain characteristics in a given experimental plot. Heretofore, prior grain measurement systems have failed to provide precise grain measurement data typically due to one of the following: a) grain moisture measurement taken on a single small sub-sample of the entire grain sample being tested; b) static weigh methods being used on a moving platform; c) the absence or poor design of volumetric chambers for density measurements on existing systems; d) user administered system calibration procedures for weight and moisture measuring devices; or e) lack of grain moisture measurement compensation for the density of the sample.
A problem with any continuous measuring system is the effect of various forces exerted on the grain harvester due to sloping surfaces and rough terrain over which the grain harvester moves. For example, the harvester will experience significant amounts of vertical acceleration (i.e., up and down motion from bouncing of the harvester) during harvesting. In addition, vibration of the harvester itself will cause errors and other problems in traditional measuring systems. Still another concern relates to making accurate measurements when the grain harvester is traversing a sloped hillside.
There is a need, therefore, to provide a grain weighing and measuring device capable of continuously measuring precise characteristics of grain being harvested with respect to weight, density, and moisture content on a plot-by-plot basis simultaneously while harvesting the grain. There is also a need to provide a grain measuring and weighing device that will account for and overcome weighing and measuring errors caused by external forces exerted on the harvester as well as the effects of moving a grain harvester across sloped surfaces.
The present invention involves a grain measuring and weighing device that measures grain samples on a continuous basis as the harvester proceeds from grain plot to grain plot. In addition, the grain harvester has a means for compensating and eliminating influences external to the grain harvester that would otherwise have an adverse effect on such measurements, such as vertical acceleration of the harvester and the effect of harvesting grain on sloped surfaces. Other advantages, features, and objects of the invention will become apparent from the detailed disclosure of the invention that follows.